We went out for dinner, and had cheesecake for dessert. Margret liked cheese cake a LOT.
Then we had a fire to sit around. When it was going nicely we put gifts for Margret on it. The gifts are symbolic - empty boxes wrapped as gifts.
We thought of all the wonderful things Margret did in her life, and told each other stories.
Celebrating her birthday without her hurts, but it hurts less than not celebrating her birthday at all.